Title: Normal Mammary Cells in Long Term Culture, II. Prolactin, Corticosterone, Insulin, and Triiodothyronine Effects on α-Lactalbumin Production*
Abstract: Cells from normal rat mammary tissue have been adapted to long term culture (up to 6 months) with retention of hormone-dependent production of α-lactalbumin (a-LA). Individual effects of added PRL, insulin, corticosterone (each at 15 μg/ml), and T3 (0.6 ng/ml) on this function of these cultured cells have been determined by RIA. An absolute requirement for corticosterone to maintain a-LA production was clearly established in cells cultured from midpregnant rats. In the presence of corticosterone, both insulin and PRL enhanced a-LA output; insulin was slightly more effective than PRL. T3 showed very little stimulation of a-LA production. By contrast, cells cultured from virginal rats had a requirement for both insulin and corticosterone for the maintenance of production of a-LA. In the presence of corticosterone and insulin, PRL enhanced a-LA production, but T3 had no significant effect. These differences of hormonal effects between cultures from pregnat and virginal rats were manifest for as long as 10 weeks after plating. Initiation of a-LA synthesis by cells initially cultured without added hormones from pregnant and virginal rats required the same hormonal additions as those shown in maintenance studies. These various hormonal combinations primarily affect a-LA synthesis (and/or degradation) but not secretion per se, since more than 95% of the a-LA produced in 24 h was secreted into the growth medium under all hormone combinations. Viable cell cultures could be maintained in either 5–14% fetal calf serum or 5–14% calf serum. The same order of importance of these four added hormones for a-LA output by cells from pregnant rats was observed in both types of sera. Thus, these differences in hormone requirements for cells cultured from pregnant or virginal animals prevail for extended periods in vitro. Our studies with long term cell cultures confirm that enhancement of a-LA production is dependent on hormones previously shown to be required for lactati nal function in other experimental models; however, we observe a much stronger dependence on added glucocorticoid than on PRL or insulin. Our observation that at least 2 weeks in culture without added hormones are required for a-LA production to fall below detectability in these cells suggests that previously reported findings using short term culture systems may need reevaluation. (Endocrinology108: 584, 1981)
Publication Year: 1981
Publication Date: 1981-02-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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Cited By Count: 21
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